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From: Camm Maguire <camm@maguirefamily.org>
To: Eli Zaretskii <eliz@gnu.org>
Cc: gcl-devel@gnu.org, emacs-devel@gnu.org
Subject: Re: utf8 and emacs text/string multibyte representation
Date: Fri, 31 Oct 2014 14:05:20 -0400	[thread overview]
Message-ID: <87h9ykazdr.fsf@maguirefamily.org> (raw)
In-Reply-To: <83wq7hzf9t.fsf@gnu.org> (Eli Zaretskii's message of "Thu, 30 Oct	2014 18:35:58 +0200")

Thanks so much!

Been discussing this elsewhere, and its come to my attention that not
only do all unicode code-points not fit into UTF-16, but all unicode
characters don't fit into unicode code-points :-).  Presumably this is
why emacs expanded to 22bits?  In any case, it makes clear what one
correspondent said, that unicode must be processed sequentially, so
there is no real reason to struggle to get random O(1) access to unicode
characters. 

If this is indeed the case, all these encodings have the same problems
though varying in degree, and UTF-8 is clearly the smallest and most
ascii compatible.  The question then arises as to whether lisp
characters, which by definition do offer random access in strings, need
be the same as or close to unicode characters.  

Did you consider leaving aref, char-code and code-char alone and writing
unicode functions on top of these, i.e. unicode-length!=length, as
opposed to making aref itself do this translation under the hood,
thereby violating the expectation of O(1) access, (which is certainly
offered in other kinds of arrays, though it is questionable whether real
users actually expect this for strings)?  In doing so, one would then
know that aref is random-access, and unicode-??? is sequential only.

Take care,

Eli Zaretskii <eliz@gnu.org> writes:

>> From: Camm Maguire <camm@maguirefamily.org>
>> Cc: emacs-devel@gnu.org,  gcl-devel@gnu.org
>> Date: Thu, 30 Oct 2014 12:27:58 -0400
>> 
>> > I'm not sure what you mean by a "boxed character".  A character in
>> > Emacs is just an int.
>> >
>> 
>> Then how do you distinguish integers from characters at the lisp level?
>
> We don't -- except that a valid character's value must fit the Unicode
> range.
>
> There's no character data type in Emacs.  (XEmacs does have it.)
>
>
>
>

-- 
Camm Maguire			     		    camm@maguirefamily.org
==========================================================================
"The earth is but one country, and mankind its citizens."  --  Baha'u'llah

  reply	other threads:[~2014-10-31 18:05 UTC|newest]

Thread overview: 136+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-10-28 22:33 Referring to revisions in the git future Alan Mackenzie
2014-10-28 22:54 ` Óscar Fuentes
2014-10-28 23:05   ` Alan Mackenzie
2014-10-28 23:24     ` Óscar Fuentes
2014-10-31 22:47     ` Paul Eggert
2014-10-29  0:49 ` Eric S. Raymond
2014-10-29  3:38   ` Stephen J. Turnbull
2014-10-29 12:26     ` Stefan Monnier
2014-10-29 12:41       ` Alexander Baier
2014-10-29 14:52   ` Barry Warsaw
2014-10-29 15:01     ` David Kastrup
2014-10-29 15:06       ` Eric S. Raymond
2014-10-29 18:12         ` Barry Warsaw
2014-10-29 22:09           ` Lars Magne Ingebrigtsen
2014-10-29 22:29             ` Eric S. Raymond
2014-10-29 23:31               ` Paul Eggert
2014-10-30  0:01                 ` Nic Ferrier
2014-10-30  1:53                 ` Stefan Monnier
2014-10-30  2:10                   ` Eric S. Raymond
2014-10-30  2:13                     ` Paul Eggert
2014-10-30  2:48                       ` Eric S. Raymond
2014-10-30  2:25                     ` Glenn Morris
2014-10-30 10:10                       ` David Kastrup
2014-10-30 13:03                         ` Stefan Monnier
2014-10-30 13:40                           ` David Kastrup
2014-10-30 14:00                             ` Stefan Monnier
2014-10-30 13:02                     ` Stefan Monnier
2014-10-30 15:12                       ` Eric S. Raymond
2014-10-30 16:49                         ` Stefan Monnier
2014-10-30  6:46                 ` Jan Djärv
2014-10-30  7:36                   ` Ivan Shmakov
2014-10-30  8:09                     ` Jan Djärv
2014-10-30  8:31                     ` Eric S. Raymond
2014-10-30  9:53                       ` Andreas Schwab
2014-10-30 10:13                         ` Eric S. Raymond
2014-10-30 10:32                           ` Andreas Schwab
2014-10-30 11:13                             ` Nicolas Richard
2014-10-30 10:12                       ` David Kastrup
2014-10-30 13:29                       ` Stefan Monnier
2014-10-30 15:33                         ` DVCS design philosophy Eric S. Raymond
2014-10-30 16:59                           ` Stefan Monnier
2014-10-30 17:41                             ` Eric S. Raymond
2014-10-31 20:18                         ` Referring to revisions in the git future Nicolas Richard
2014-10-31 21:11                           ` Stefan Monnier
2014-11-01  1:44                             ` Stephen J. Turnbull
2014-11-01  7:58                             ` David Kastrup
2014-10-30 14:20                       ` Barry Warsaw
2014-11-01  1:23                         ` Stephen J. Turnbull
2014-10-30 15:52                     ` Eli Zaretskii
2014-10-30  3:32           ` Stephen J. Turnbull
2014-10-30  4:35             ` Barry Warsaw
2014-10-30  5:24               ` Stephen J. Turnbull
2014-10-30 10:17               ` David Kastrup
2014-10-30 13:42               ` Alex Bennée
2014-10-30 13:19             ` Stefan Monnier
2014-10-31  6:36               ` Stephen J. Turnbull
2014-10-31 19:42               ` David Kastrup
2014-11-01  1:34                 ` Stephen J. Turnbull
2014-11-01  7:05                   ` Tassilo Horn
2014-11-01  7:09                     ` Dima Kogan
2014-11-01  7:28                     ` Paul Eggert
2014-11-01  7:49                     ` David Kastrup
2014-11-01  9:46                       ` Alan Mackenzie
2014-11-01 10:13                         ` Eli Zaretskii
2014-11-01 11:33                           ` Alan Mackenzie
2014-11-01 13:06                             ` Eli Zaretskii
2014-11-01 13:21                               ` Alan Mackenzie
2014-11-01 10:29                         ` David Kastrup
2014-11-01 11:29                           ` Alan Mackenzie
2014-11-01 11:57                             ` David Kastrup
2014-11-01 12:29                               ` Alan Mackenzie
2014-11-01 12:47                                 ` Ivan Shmakov
2014-11-01 13:46                                   ` Alan Mackenzie
2014-11-01 18:58                                     ` Stephen J. Turnbull
2014-11-01 12:49                                 ` David Kastrup
2014-10-29  1:11 ` Stefan Monnier
2014-10-29  6:06   ` Werner LEMBERG
2014-10-29  9:01     ` David Kastrup
2014-10-29  8:50 ` David Kastrup
2014-10-29  9:52   ` Eric S. Raymond
2014-10-29 11:00     ` David Kastrup
2014-10-29 14:32       ` Eli Zaretskii
2014-10-29 14:35         ` David Kastrup
2014-10-29 14:55           ` Eli Zaretskii
2014-10-30  4:44             ` Richard Stallman
2014-10-30  8:32               ` Eric S. Raymond
2014-10-30 10:25                 ` David Kastrup
2014-10-30 11:51                   ` Eric S. Raymond
2014-10-30 12:14                     ` David Kastrup
2014-10-30 15:01                       ` Eric S. Raymond
2014-10-30 15:53                 ` Eli Zaretskii
2014-10-30 15:56                   ` Eric S. Raymond
2014-10-30 16:44                     ` Eli Zaretskii
2014-10-31  7:47                 ` Richard Stallman
2014-10-31  8:17                   ` Eli Zaretskii
2014-10-31 10:21                   ` Eric S. Raymond
2014-10-29 12:35     ` Stefan Monnier
2014-10-29 13:00       ` Jose E. Marchesi
2014-10-29 13:59         ` Stefan Monnier
2014-10-29 14:39           ` Eric S. Raymond
2014-10-29 14:46             ` Rasmus
2014-10-29 14:52               ` Eric S. Raymond
2014-10-30  0:58               ` Rob Browning
2014-10-29 15:27             ` Stefan Monnier
2014-10-29 14:04         ` utf8 and emacs text/string multibyte representation Camm Maguire
2014-10-29 14:51           ` Eli Zaretskii
2014-10-29 15:55             ` Camm Maguire
2014-10-29 16:19               ` Eli Zaretskii
2014-10-30 14:13                 ` Camm Maguire
2014-10-30 16:06                   ` Eli Zaretskii
2014-10-30 16:27                     ` Camm Maguire
2014-10-30 16:35                       ` Eli Zaretskii
2014-10-31 18:05                         ` Camm Maguire [this message]
2014-11-01  9:01                           ` Eli Zaretskii
2014-11-01 18:32                             ` Stephen J. Turnbull
2014-11-01 18:41                               ` David Kastrup
2014-11-01 19:09                                 ` Stephen J. Turnbull
2014-11-02  0:56                                 ` Stefan Monnier
2014-11-01  1:16                         ` Stephen J. Turnbull
2014-10-29 16:45             ` Stefan Monnier
2014-10-29 15:56           ` Raymond Toy
2014-10-30 14:16             ` Camm Maguire
2014-10-31 18:47               ` Sam Steingold
2014-10-31 21:00                 ` Andreas Schwab
2014-10-31 19:52               ` [Gcl-devel] " Stefan Monnier
2014-10-30  3:08           ` Stephen J. Turnbull
2014-10-29 13:26       ` Referring to revisions in the git future Eric S. Raymond
2014-10-29 14:04         ` Stefan Monnier
2014-10-29 14:49           ` Eric S. Raymond
2014-10-30  2:43           ` Stephen J. Turnbull
2014-10-29 13:08     ` Jan Djärv
2014-10-29 13:27       ` Eric S. Raymond
2014-10-29 13:49         ` Eric S. Raymond
2014-10-29 18:03           ` Jan Djärv
2014-10-29 11:18   ` Alan Mackenzie
2014-10-29 11:37     ` David Kastrup

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